2.6.38-stable review patch. If anyone has any objections, please let us know.

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From: Kees Cook <kees.cook@canonical.com>

commit 5883f57ca0008ffc93e09cbb9847a1928e50c6f3 upstream.

While mm->start_stack was protected from cross-uid viewing (commitf83ce3e6b02d5 ("proc: avoid information leaks to non-privilegedprocesses")), the start_code and end_code values were not. This wouldallow the text location of a PIE binary to leak, defeating ASLR.

Note that the value "1" is used instead of "0" for a protected value since"ps", "killall", and likely other readers of /proc/pid/stat, takestart_code of "0" to mean a kernel thread and will misbehave. Thanks toBrad Spengler for pointing this out.